Haemolytic disease

• What is haemolytic disease of the newborn (HDN)?


  Immunological condition

  Arises when a rhesus negative mother becomes sensitised to the rhesus positive blood cells of baby while in utero
• Pathophys - haemolytic disease of the newborn (HDN)


  Rhesus negative mother exposed to rhesus positive foetal RBCs -> mother's immune system produces IgG antibodies against rhesus antigen -> in subsequent pregnancies, memory B cells rapidly produce IgG upon exposure to rhesus positive RBCs -> maternal antibodies cross placenta & bind to foetal RBCs -> destruction of foetal RBCs (extravascular haemolysis) in foetal spleen -> foetal anaemia
• What are the RFs of haemolytic disease of the newborn?


  Hx of rhesus positive foetus in rhesus negative mother

  Fetomaternal haemorrhage

  Invasive foetal procedures

  Placental trauma

  Omission of rhesus immunoprophylaxis
• What are the signs & symptoms of haemolytic disease of the newborn?


  Hydrops foetalis -> appearing as foetal oedema in at least 2 compartments, seen on antenatal ultrasound

  Yellow coloured amniotic fluid -> due to excess bilirubin

  Neonatal jaundice & kernicterus

  Foetal anaemia -> skin pallor

  Hepatomegaly/splenomegaly

  Severe oedema if hydrops foetalis was present in utero
• What are the DDx of haemolytic disease of the newborn?


  Spherocytosis

  G6PD deficiency

  Thalassemia
• What are the Inx for haemolytic disease of the newborn?


  Direct Antiglobulin Test (DAT)

  Ultrasound to detect foetal oedema

  LFTs -> check for complications
• What is the management of haemolytic disease of the newborn?


  Intrauterine transfusions - if severe anaemia is detected in foetus

  Early delivery (if severe)

  Postnatal -> phototherapy or exchange transfusion (to manage jaundice)

  Immunoglobulin administration to neonate -> prevent further haemolysis

  Regular follow up -> to assess developmental issues
• ABO antigens are not expressed on RBCs until 16 wks after birth. So, in neonates there is no need to crossmatch for blood transfusions.